Rewinding machine and method for producing variously sized paper logs

ABSTRACT

The invention refers to a rewinding machine and a method for producing logs of paper; the machine comprises means for feeding a continuous paper web ( 2 ) along a predetermined path, means for operating a series of discontinuous transverse cuts in order to subdivide the web ( 2 ) into portions of sheets of predetermined length to be separated by tear, means for feeding tubular cores ( 1 ) upon each of which a preset number of sheets is to be wound to form a log, a cores ( 1 )-guiding channel (C) which extends between a cores ( 1 )-feeding station (A) and a station at which a log (RO) is formed, the said channel (C) being delimited in part by a fixed guide ( 3 ) and in part by a roller (RA) which cooperates for the feeding of the paper ( 2 ); the machine comprises a device ( 4, 5; 32, 31 ) able to deliver predetermined amounts of glue within said channel (C), the said device including first and second means ( 4, 31; 5, 32 ) located and acting on corresponding preset points being located between the station (A) for feeding the cores ( 1 ) and the station for forming the logs (RO).

[0001] The present invention refers to a rewinding machine and a methodfor producing paper rolls (so-called “logs” in the technical jargon) ofvarious size.

[0002] The production of logs is known to require the supply of acontinuous paper web along a predetermined path. At a point of saidpath, a discontinuous transverse cut is operated on the web in order tosubdivide it into portions or sheets of preset length to be separated bya tear.

[0003] The formation of logs implies the use of tubular cardboard spools(commonly referred to as “cores”) on the surface of which a presetamount of glues is distributed to allow the glueing of the first sheetof the log to be formed.

[0004] The said formation makes also use of winder rollers which drivethe core, on which the paper winds up, into rotation.

[0005] The process of formation of a log terminates after a presetamount of paper has been wound over the core. At this point, theformation of the next log is started.

[0006] Upon completion of the said formation it is necessary to glue thelast sheet of each log on the underlying sheet, to avoid the spontaneousunwinding of the same log. This type of glueing is defined “edgeclosing”.

[0007] To this end, downstream of the unit for the formation of the loga suitable glueing device is provided to which all the formed logs arefed. Each log is to be cut transversally afterwards, to obtain therefroma plurality of rolls of paper of commercial format.

[0008] A rewinding machine for the production of logs is described indetails in the patent EP 694020.

[0009] The above described technique of forming a log requires thereforean auxiliary device for glueing. This weighs heavily on the runningcosts and demands more space for the production system.

[0010] There are also other considerations to be made on the abovetechnique. One important aspect to be considered relates to theprocedure for spreading the glue onto the core, as necessary to fix thefirst sheet of the log to be formed. On the machines presently known,this procedure is carried out outside the winding region: the glue isdistributed onto the cores to be used afterwards for the formation ofthe log, prior to the same cores entering the region in which they comein contact with the paper web. This operating mode, in the case of aprolonged stop of the machine, may lead to the drying of the gluepresent onto the cores. It should be understood that such a situation,if not suitably rectified, leads to a faulty process. In fact, on themachines of this type, the operator is bound, under such conditions, toremove manually the core previously glued.

[0011] A further consideration, again concerning the glue spread ontothe core, refers to the stage in which the size of the log becomesincreasingly larger between the winding rollers. The weight of the glueapplied onto the core, in the case the latter is distributedlongitudinally on a rather thick line, is cause for an “unbalance” ofthe same core which, when considering the speed involved, may inducestrong vibrations on the log in the course of formation. Thisphenomenon, which can be self-intensifying, may lead to the formation ofa log in which the core results out of axis.

[0012] The main object of the present invention is to overcome the saiddrawbacks.

[0013] This result has been achieved, according to the invention, byadopting the principles disclosed in the independent claims. Furthercharacteristics being set forth in the dependent claims.

[0014] The present invention makes it possible to avoid using glueingdevices of “edge closing” type with significant advantages, as far ascost and space are concerned. Moreover, it allows overcoming the saiddrying and “unbalance” problems above described.

[0015] The said advantages and other characteristics of the inventionwill be best understood by anyone skilled in the art from a reading ofthe following description in conjunction with the attached drawingsgiven only as a practical exemplification of the invention and not to beconsidered in a limitative sense. In the drawings:

[0016]FIG. 1 is a schematic illustration of a machine according to theinvention;

[0017]FIG. 2 shows an enlarged detail of the drawing of FIG. 1;

[0018]FIGS. 3-10 shows schematically a sequence of steps relating to theoperation of the machine of FIG. 1;

[0019]FIG. 11 is a schematic view in longitudinal section of the firstmeans for the application of glue in inoperative or stand-by condition;

[0020]FIG. 12 shows the means of FIG. 11 in operative condition;

[0021]FIG. 13A is a partial side view of a possible embodiment of theblade for the means of FIGS. 11 and 12, in which the blade has thin andspaced apart teeth;

[0022]FIG. 13B is a front view of the blade of 13A;

[0023]FIG. 14 is a partial side view of a possible embodiment of theblade for the means of FIGS. 11 and 12, in which the blade has largeteeth;

[0024]FIG. 14B is a front view of the blade of FIG. 14A;

[0025]FIG. 15A is a partial side view of a possible embodiment of theblade for the means of FIGS. 11 and 12, in which the blade has acontinuous, non-toothed profile;

[0026]FIG. 15B is a front view of the blade of FIG. 15A;

[0027]FIG. 16 is a schematic illustration of further embodiment of theinvention and;

[0028]FIGS. 17-28 show schematically a machine according to theinvention, in different sequential operating steps, with a furtherexemplary embodiment of the guide channel for the cores.

[0029] Reduced to its basic structure, and reference being made to thefigures of the attached drawings, a machine according to the inventioncomprises:

[0030] a station (A) for feeding the cores (1);

[0031] a store (M) for housing the cores (1);

[0032] means for supplying the station (A) with cores (1) removed fromthe store by a chain delivery system (N) extending between the station(M) and station (A);

[0033] means for feeding and transversally pre-cutting or perforatingthe paper (2) by means of a plurality of feeding, driving, and cuttingrollers (R1, R2, R3, RA) disposed along a predetermined path whichincludes also the station (A) for the supply of cores (1);

[0034] means for rolling up the paper (2) onto the core (1) by means oftwo winder rollers (RA, R4, R5), the two rollers (R4 and R5) of whichoverlap at the outlet of a channel (C) being delimited by a fixedcurvilinear guide (3) and the surface of roller (RA).

[0035] The roller (RA) has the dual function of feeding the paper (2)and winding it onto the core (1), as will be best described later.

[0036] The above said channel (C) delimits the last stretch of the pathcovered by the paper (2) and also the path followed by each core (1)which leaves the core-feeding station (A) and moves towards the exit ofchannel (C).

[0037] Advantageously, according to the invention, first and secondmeans (4, 5) are provided for delivering a preset amount of glue ontothe surface of each core (1) introduced into the channel (C). Saidglue-delivering means (4, 5) act in correspondence of the channel (C)according to a precise sequential order. This provides for the firstdelivery of the glue to the last sheet of log (RO) in the course offormation and, then, for the delivery of glue intended to attach thefirst sheet of a new log on a corresponding core (1) suitably introducedinto the channel (C).

[0038] As will be best described later on, the delivery of glue by thefirst and second means (4, 5) is alternated by the transit of aperforation line (p) which separates the last sheet of log (RO) in thecourse of formation from the first sheet of the next log to be formed.

[0039] More particularly, and reference being made to the FIGS. 3-10,the normal operating condition takes place as described below.

[0040] After winding a preset number of sheets onto the core (1) of log(RO) under formation, the lever (6), which introduces the core (1)standing by at the station (A) (FIG. 3), operates the introduction ofone core (1) into the channel (C) by rotating about its axis (60) andpushing the same core from the back (FIG. 4). Upon this stage, theformation of the log (RO) continues on the opposite side of channel (C),so that the paper continues to wind up onto the relevant core (1 r) bymeans of the winder rollers (RA, R4, R5).

[0041] The core (1), freshly introduced into the channel (C), begins toadvance and to roll at the same time by virtue of the contact of itssurface with the surface of the roller (RA) which rotates about its ownaxis, as indicated by the arrow (U).

[0042] During the step in which the core (1) is introduced into thechannel (C), the angular speed of roller (R5) is decreased with respectto that of roller (RA) and roller (R4). This situation causes the logunder formation (RO) to move away from the surface of roller (RA). Theangular speed of roller (R4) is then set equal to that of roller (R5).The speed difference between roller (R5) and roller (RA) determines areduction of tension and, therefore, a loosening of the paper web (2)upstream of rollers (R4, R5) and implies also a detachment of the paperfrom the surface of roller (RA) (FIG. 4). This detachment occurs alongthe channel (C) over a length extending between the core (1) and winderrollers (R4, R5). The detachment of the paper from roller (RA) can bemade easier by a blow of compressed air through a nozzle (7) actingbetween the surface of roller (RA) and the station of the winder rollers(R4, R5). As an alternative to the blow operated through the nozzle (7),a suction may be operated on the side of guide (3). In the drawings,(VU) denotes a suction unit.

[0043] When the core (1), by virtue of its advancing along the channel(C), arrives in correspondence of the first glue-delivering means (4),these are activated and, accordingly, a preset amount of glue is appliedon the surface of core (1) (FIG. 5). When this core (1) arrives incorrespondence of the second glue-delivering means (5), these areactivated as well (FIG. 6). The distance between the first (4) andsecond (5) means is properly selected so that, in correspondence of thesecond means (5), the core (1) will result rotated through an anglerelative to the position taken up in correspondence of the first means(4) (FIG. 6). In any case, the perforation line (p) on the paper (2)results included between the regions (q, a) subjected to the actions ofthe first and second glue-delivering means (4, 5). In this way, thedelivery of the glue by the first means (4) will interest the last sheetof log (RO) under formation, while the delivery of glue by the secondmeans (5) will cause the glueing on the core (1) of the first sheet ofthe new log under formation.

[0044] As shown in greater detail in FIG. 6, when the core (1), owing toits combined advancement and rolling up along the channel (C), arrivesover the second glue-delivering means (5), the region (q) of paper web(2) comes in contact with the region of core (1) previously interestedby the action of the first glue-delivering means (4). Depending on theposition of said glue-delivering means (4, 5), the region (q) resultsoffset by a well defined angle relative to the region (a) of core (1)onto which the second means (5) are made to act. FIG. 6 shows the casein which the position of said means (4, 5) is such that the region (q)and (a), acted upon by means (4, 5), result diametrically opposite onthe core (1), so that the said angle is of approximately 180°.

[0045] The core (1), by moving and rolling up forwards along the channel(C), transfers most of its glue, applied by the means (4), to the region(q′) of the paper web. The region (q) belongs to the last sheet of log(RO) under formation inasmuch as it results downstream of theperforation line (p) which defines the end of the same log (RO). Inpractice, an edge (q′) of the last sheet of log (RO) under formationresults thus glued, that is, provided with glue, at some distance fromline (p): the core (1) makes up the means by which the glue is appliedon the last sheet of the log (RO) since, at least in part (though insufficient amount), the glue is transferred by contact from the core(region q) to the paper (edge or region q′).

[0046] By keeping on along its path, the core (1) passes also the secondglue-delivering means (5) and, by virtue of its rolling up along thechannel (C), also the region (a) of the same core (1) arrives in contactwith the paper web (2), at a region of the sheet which follows the line(p). This sheet is the first one of the subsequent log to be formed. Theglue in the region (a) is such as to cause the paper web (2) to adhereonto the core (1) which web, in the meantime and as previouslymentioned, has become somewhat loose in the region between the core (1)and the end of the channel (C), by virtue of the reduction of speed ofthe winder rollers (R4, R5) with respect to roller (RA) (FIG. 7).

[0047] The loosening effect of the paper web (2), in combination withthe adhesion of the same web onto the core (1) caused by the gluepresent in the region (a), is such that, during the rolling up of core(1), there is occurs a progressive winding of the paper web (2) onto thecore (1) (FIG. 7). Thereafter, in correspondence of the terminal portion(30) of the guide (3), the first sheet of the next log to be formedresults fitted (again by the effect of rolling and advancement of core(1)) between the surface of the said portion (30) and the surface ofcore (1) (see FIG. 8). Owing to this, and to the fact that the winderrollers (R4, R5) keep on rotating, the part of the paper web (2) whichresults compressed between the surface (30) of guide (3) and the log(RO) under formation is subjected to such a tensioning as to cause atear in correspondence of the line (p), as shown in FIG. 9.

[0048] By keeping on to rotate, the winder rollers (R4, R5) complete theformation of the log (RO) with the passage of the glued region (q′) ofthe log's last sheet under the roller (R4). This causes thecorresponding glueing of the last sheet of log (RO) upon thatimmediately below of the same log (FIG. 10). At this point, the speed ofroller (R4) is increased and, by virtue of the speed difference thuscreated between the winder rollers (R4, R5), the log (RO) underformation is released and made to slide along a discharge guide (9)downstream of the winder rollers (R4, R5). Following this step, therollers (R4, R5) reach again the running speed, and the place of (RO) istaken by the core (1) advancing towards the end part (30) of the guide(3) to allow the formation of a new log.

[0049] It will be appreciated that the interventions of said first andsecond glue-delivering means are suitably synchronized to each other toobtaining what has been previously described, and that the paper (2) issupplied with continuity onto the surface of the roller (RA) also duringthe advancement of the core (1) along the channel (C).

[0050] The winder roller (R4) is mounted on a corresponding support arm(400) which is hinged to a stationary part of the machine and isassociated with an actuator (410) which allows it to be moved close to,and away from the lower winder roller (R5) in a manner known to thoseskilled in the art.

[0051] The above described operations can be performed automaticallythrough programmable electronic means known to those skilled in the artand, therefore, will not be described in greater details.

[0052] From the above description of the machine and operating procedureit can be seen that it is possible to avoid using any glueing devicedownstream of the winder rollers, with evident economical advantagesderived both from direct savings and the smaller space required for theplant. Also evident are the advantages derived from the novel system oftransferring the glue onto the core: the glueing carried out within thewinding region overcomes the problems due to the drying of the glue(which glue, by fulfilling immediately its function, is not subject todry), and the application of a dual longitudinal line reduces the“unbalance” problems, as the regions of glue application formsubstantially two lines diametrically opposite with respect to thesurface of the core (1).

[0053] The first glue-application means (4) may comprise, with referenceto the examples of FIGS. 11 and 12, a liquid-glue-holding reservoir (40)located below the guide (3), and a blade (41) provided inside saidreservoir and movable from and to the channel (C) under control of acorresponding actuator (42) connected thereto via a chain of rigidtransmissions (43, 44, 45). In the condition shown in FIG. 11, the blade(41) is fully held within the reservoir (40). In the condition shown inFIG. 12, the blade (41) is lifted by the withdrawal of the rod ofactuator (42) and by the corresponding movements (as shown by thearrows) of members (43, 44, 45) of the transmission system. The liftingof blade (41) causes the application of the glue upon the surface ofcore (1) which, on that moment, is transiting along the channel (C). Itwill be appreciated that the guide (3) is suitably slotted to allow thelifting of the blade (41) and the contact thereof with the surface ofblade (1). As illustrated in FIGS. 13A, 14A and 15A, the upper edge ofthe blade (41) may be either discontinuous, that is, provided with atoothing (FIGS. 13A and 14A), or continuous (FIG. 15A). Besides, asshown in FIGS. 13B, 14B and 15B, the upper edge of the blade (41) may beconcave, with concavity turning upwards.

[0054] The second glue-application means (5) can be made like the firstones (4) and their description, therefore, will not be repeated.

[0055] Obviously, the number of sheets of each log (RO) and the lengththereof may be as desired.

[0056] According to a further embodiment of the present invention, andwith reference to FIG. 16, the glue can be delivered through twoinjectors (32, 31) intended for delivering the glue direct onto thepaper (2) upstream and respectively downstream of a perforation line (p)which separates the last sheet of log (RO) under formation from thefirst sheet of the next log to be formed. The activation of saidinjectors (32, 31) can be concurrent, as schematically illustrated inFIG. 16.

[0057] As in the case previously described, the injectors (32, 31) arepositioned within said channel (C) at a preset distance one from theother.

[0058] With reference to the examples of FIGS. 17-28, the stationaryguide of said channel (C) is into two elements:

[0059] a first element (3 a) is opposite to an underlying conveyor belt(300) ring-like closed and located immediately downstream of the section(A) which feeds the tubular cores (1);

[0060] a second element (3 b) is located downstream of the first element(3 a) and of said belt (300), opposite to roller (RA). The schematicrepresentations of FIGS. 17-22 and respectively of FIGS. 23-28 differfrom each other only for the different positioning of theglue-delivering means which, in any case, act within the said channel(C) and are positioned at a preset distance from each other. Theglue-delivering procedures can be combined as in FIGS. 17-22 where thefirst glue-delivering means are of blade type, and the second deliveringmeans are of injection type.

[0061] Practically, all the construction details may vary in anyequivalent way as far as the shape, dimensions, elements disposition,nature of the used materials are concerned, without neverthelessdeparting from the scope of the adopted solution idea and, thereby,remaining within the limits of the protection granted to the presentpatent for industrial invention.

1. Rewinding machine for producing logs of paper, comprising means forfeeding a continuous paper web (2) along a predetermined path, means foroperating a series of discontinuous transverse cuts in order tosubdivide the web (2) into portions or sheets of predetermined length tobe separated by tear, means for feeding tubular cores (1) upon each ofwhich a preset number of sheets is to be wound to form a log, acores-guiding channel (C) which extends between a cores-feeding station(A) and a station at which a log (RO) is formed, the said channel (C)being delimited in part by a fixed guide (3) and in part by a roller(RA) which cooperates for the feeding of the paper (2), characterized inthat it comprises a device (4, 5; 32, 31) able to deliver predeterminedamounts of glue within said channel (C), the said device including firstand second means (4, 31; 5, 32) located and acting on correspondingpreset points of said channel (C), the said preset points being locatedbetween the station (A) for feeding the cores (1) and the station forforming the logs (RO).
 2. Machine according to claim 1, characterized inthat it comprises first and second means (4, 5) for applying a presetamount of glue onto the surface of each core (1) which transits, thatis, moves forward and rolls up, along the said channel (C).
 3. Machineaccording to claim 2, characterized in that said first and second means(4, 5) can be activated on different times.
 4. Machine according toclaim 1, characterized in that said first and second means (4, 5) can beactivated in sequence, the relevant activation sequence including thetransit of a cut line (p) which separates the last sheet of log (RO)under formation from the sheet of the next log to be formed.
 5. Machineaccording to claim 1, characterized in that it comprises pneumatic means(7; VU) to facilitate the detachment of the paper (2) from the surfaceof said roller (RA)
 6. Machine according to claim 5, characterized inthat pneumatic means are located upstream of the logs (RO)-formingstation.
 7. Machine according to claim 1, characterized in that itcomprises first and second means (30, 31) for injecting preset amountsof glue on different points of the paper web (2).
 8. Machine accordingto claim 7, characterized in that said first and second means (30, 31)can be activated at the same time.
 9. Method of producing logs of paper,comprising the steps of: feeding a continuous paper web (2) along apredetermined path; operating a series of discontinuous transverse cutsin order to subdivide the web (2) into portions or sheets ofpredetermined length to be separated by tear; feeding tubular cores (1),upon each of which a preset number of sheets is to be wound to form alog, along a cores-guiding channel (C) which extends between acores-feeding station (A) and a station at which a log (RO) is formed;the said channel (C) being delimited in part by a fixed guide (3) and inpart by a roller (RA) which cooperates for the feeding of the paper (2),characterized in that it includes applying a predetermined amount ofglue upon the surface of each core (1) which transits, that is, movesforward and rolls up, along said channel (C), or upon predeterminedpoints or edges of the web (2) that transits along said channel (C), thesaid application of glue being operated in correspondence of the transitof each core (1) through at least a point of said channel (C) which isintermediate between the cores-feeding station (A) and the station forthe formation of logs (RO).
 10. Method according to claim 9,characterized in that the said application of glue is operated incorrespondence of the transit of each core (1) through two distinctpoints of said channel (C).
 11. Method according to claim 9,characterized in that the application of the glue concerns two distinctregions (a, q) of each core (1).
 12. Method according to claim 9,characterized in that the application of the glue concerns twodiametrically opposite regions (a, q) of each core (1).
 13. Methodaccording to claim 9, characterized in that between the applications ofthe glue upon said regions (a, q) of each core (1) there is occurs thetransit of a paper-cutting line (p) which separates the last sheet ofthe log (RO) under formation from the first sheet of a subsequent log tobe formed
 14. Method according to claim 9, characterized in that alongsaid channel (C) each core (1) applies the glue, by contact, at a presetdistance from said cut line (p), upon an edge (q′) of the last sheet ofthe log (RO) in the course of formation.
 15. Method according to claim9, characterized in that the said glue application concerns directly thepaper web (2) and is operated upon the transit of each core (1) througha preset point of said channel (C).
 16. Method according to claim 1,characterized in that it includes a tear-operated detachment of the lastsheet of the log (RO) under formation, from the first sheet of asubsequent log to be formed, by virtue of a paper's tensioning as aresult of fitting said first sheet between the surface of thecorresponding core (1) and a fixed surface of said guide (3). 17.Machine according to claim 2, characterized in that said first andsecond means (4, 5) can be activated in sequence, the relevantactivation sequence including the transit of a cut line (p) whichseparates the last sheet of log (RO) under formation from the sheet ofthe next log to be formed.
 18. Method according to 10, characterized inthat the application of the glue concerns two distinct regions (a, q) ofeach core (1).
 19. Method according to claim 10, characterized in thatthe application of the glue concerns two diametrically opposite regions(a, q) of each core (1).